UPDATE, 7:10 P.M. - A third person has died following the explosion in East Harlem. The City said nine people were still missing Wednesday night and 69 people suffered injuries.

WESTCHESTER COUNTY, N.Y. -- New York City Mayor Bill DeBlasio confirmed two people were killed and two buildings were destroyed by an explosion in Harlem caused by a gas leak on Wednesday morning during a 12:30 p.m. press conference.

The two buildings included 15 residential units and DeBlasio confirmed that 18 people are injured, calling the incident "a tragedy of the worst kind." DeBlasio added that there are an unconfirmed number of missing people as well, but added that some of the missing may be alive and well in other parts of the city.

A smell of gas was reported at 9:13 a.m. to Con Edison in a neighboring building next to the ones that were destroyed by the explosion at 9:31 a.m.

New York Fire Department Commissioner Sal Fasano said at the press conference that crews are working to remove heavy debris from the sidewalk and the surrounding area.

Debris also was strewn on the Metro-North train tracks that are less than 100 yards from the building, shutting down commuter rail service to and from Grand Central Station. Commuters are advised to seek alternate routes to and from New York City, but Metro-North officials are hopeful service will be restored by rush hour on Wednesday.